Process for dissolving sodium,potassium and their alloys

ABSTRACT

A PROCESS FOR THE DISSOLUTION OF SODIUM, POTASSIUM AND/ OR THEIR ALLOY AFTER IRRIDATION IN WHICH THE MATERIAL FOR DISSOLUTION IS SUBJECTED TO THE ACTION OF ALCOHOL IN AN ARGON ATMOSPHERE THE REACTION TAKING PLACE IN THE PRESENCE OF A LIQUID SOLUBLE IN ANY PROPORTION IN THE ALCOHOL, THE AMOUNT DISSOLVED BEING DETERMINED TO CONTROL THE REACTION. APPARATUS FOR CARRYING OUT THE PROCESS INCLUDING SLEEVES TO ENGAGE THE ENDS OF AN IRRIDATION CAPSULE HOLDING THE MATERIAL, ONE SLEEVE BEING COUPLED TO A FLUID INLET AND THE OTHER VIA A VALVE TO A TANK WHICH HAS AN INLET FOR ARGON, A SAFETY VALVE AND TWO GLOVE-BOX TEMPERATURE MEASURING POINTS.

April 30, 1974 B MANSARD 3,808,141

PROCESS FOR DISSOLVING SODIUM, POTASSIUM AND THEIR ALLOYS Filed Sept 15,1970 2 sheets-sheet 1 INVENTOR BERNARD MANSARD BY Graig, Hntonelli,Shaun-"L HUI.

I ATTORNEYS April 30, 1914 PROCESS FOR DISSOLVING SODIUM.

Filed Sept. 15, 1970 B. MANSARD POTASSIUM AND THEIR ALLOYS 2Sheets-Shoot 2 FIG2 INVENTOR BERNARD MANSARD BY G 3, nntoneui, Shaman-l;ATTORNEYS United States Patent 3,808,141 PROCESS FOR DISSOLVING SODIUM,POTASSIUM AND THEIR ALLOYS Bernard Mansard, Saint-Cyr-LEcole, France,assignor to Commissariat a lEnergie Atomique, Paris, France Filed Sept.15, 1970, Ser. No. 72,366 Claims priority, appligtggrirllgrance, Sept.17, 1969,

Int. Cl. G21c 19/42 US. Cl. 252301.1 R 7 Claims ABSTRACT OF THEDISCLOSURE A process for the dissolution of sodium, potassium and/ ortheir alloy after irradiation in which the material for dissolution issubjected to the action of alcohol in an argon atmosphere the reactiontaking place in the presence of a liquid soluble in any proportion inthe alcohol, the amount dissolved being determined to control thereaction. Apparatus for carrying out that process including sleeves toengage the ends of an irradiation capsule holding the material, onesleeve being coupled to a fluid inlet and the other, via a valve to atank which has an inlet for argon, a safety valve and two glove-boxtemperature measuring points.

The invention relates to a process and apparatus for dissolving sodium,potassium and their alloys, after the latter have been irradiated,generally while contained in an irradiation capsule. The invention ismore particularly concerned with a process and apparatus of this kindfor dissolving the equi-atomic alloy of sodium and potassium, NaK, in analcohol under an inert argon atmosphere.

We have used such a process and apparatus for a long time and have foundthe process satisfactory for amounts of NaK up to 200 cm. it hasdisadvantages or is even dangerous when the amount of NaK exceeds 200cm. as is the case with larger capacity irradiation assemblies whichhave since come into use, since the reaction of the alcohol on the NaKis highly exothermic, and when the amount of NaK reaches 400-600 cm asit often does, the existing process and apparatus become inadequate todissipate the excess heat of reaction which then very quickly becomesuncontrollable: the alcohol boils; the alcohol vapors, mixed with thehydrogen formed, evolve violently; the alcohol overflows and lifts thelid of the receptable whose section is too small. Clearly, this methodis risky, having regard to the relatively large amount of alcohol (ofthe order of 20 liters) which must be used to dissolve the NaKcompletely.

It is the main object of the invention so to adapt the processes andapparatuses of the kind specified that they meet more satisfactorilythan hitherto various practical requirements, inter alia enable thedissolution reaction to be controlled and performed in an improvedapparatus which increases safety and saves time and raw materials, asregards the total amount of alcohol used.

The main feature of the process according to the invention is that itconsists in subjecting sodium, potassium and/or their alloy to theaction of an alcohol in an inert argon atmosphere, the reaction takingplace in the presence of a liquid soluble in any proportions in thealcohol, the reaction being controlled by varying the amount of alcoholdissolved in the liquid.

The invention also relates to an apparatus for the performance of theprocess, the apparatus being characterized in that it comprises twosealing-tight sleeves which can be connected to the two ends of anirradiation capsule containing the sodium, potassium and/or their alloyto be dissolved, the first sleeve being connectable to a fluid inletpipe and the second sleeve being connectable 3,808,141 Patented Apr.30,1974

via a spherical plug valve to the lid of a wide-aperture tank, the lid,disposed on the tank without any gasket, comprising a shaft connectingwith a tube of the plug valve, an argon inlet continued in the form of atube whose lower portion is curved and which extends into the tank, anda safety valve, the tank having two glove-box temperature measuringpoints disposed in parallel and downwardly orientated at an angle of 45with the tank wall.

Apart from these main features, the invention also relates to certainother features which are preferably used simultaneously, inter alia:

The liquid soluble in any proportions in the alcohol is a kerosene-basedmachining fluid;

The sealing-tight sleeves are of the kind disclosed in the French patentapplication filed in the applicants name on Sept. 16, 1969 for:Sealing-Tight Connecting Sleeve;

The spherical plug valve is of the direct-control and A-turn open-closetype;

The lid has a flange to locate it on the tank;

The connecting shaft in said lid comprises laterally a wing-type pointscrew to lock the valve tube against rotation;

The lower portion of the curved tube is tangential to both the bottomand wall of the tank and is flattened in ducks bill shape at its end;

The lid has ribs at along its radii, the ribs being formed withlarge-diameter holes enabling the lid to be handled,

The tank is cylindrical;

The side wall of the tank comprises two diametrically opposite liftinglugs;

The lower portion of the tank comprises a telemanipulation point, interalia a ring;

The top edge of the tank comprises a pouring lip.

In any case, the invention will be clearly understood from the followingdescription, with reference to the accompanying drawings, bothdescription and drawings being merely exemplary and non-limitative, inwhich:

FIG. 1 is a vertical sectional view of the apparatu according to theinvention, and

FIG. 2 is a detail of one of the sealing-tight connecting sleeves usedin the apparatus illustrated in FIG. 1.

As already stated, it is an object of the method according to theinvention to enable the dissolution reaction to be controlled.

As a rule, when sodium, potassium or NaK is placed in alcohol, it isfound to react immediately, rise to the surface, thus limiting thevolume of useful alcohol, and agglomerate in clots.

To control dissolution, steps must therefore be taken to retard, start,stop and perform the reaction as required, and then to dissipate theheat evolved.

To retard the reaction and prevent the NaK (or Na, or K) from reactingspontaneously with the alcohol onits emergence from the irradiationcapsule or even therein, it is driven out with a chemically inert liquidand received in the same liquid.

To start the reaction at the required time, it is enough for the liquidto be soluble in any proportions in the alcohol, since the dissolutionof the NaK which the liquid contains can then be started by adding asuitable amount of the alcohol thereto.

The reaction stops automatically when there is no longer enough alcoholin the solution.

To perform the reaction as required, it is then enough to add alcohol insmall amounts, thus also enabling the reaction temperature to becontrolled.

The reaction takes place at the surface of the liquid, the heat will bemore readily dissipated in proportion as the receptacle section isincreased (thus also reducing the risk of convection) and the specificmass and exchange surface are also increased, and in proportion as avolume of inert, preferably non-flammable liquid is available inadjustable amounts to homogenize the temperature, and the liquid iscontinuously violently agitated to prevent hot spots and break up thelarge lumps of NaK. If agitation is performed by a gas stream thetemperature can also be lowered as required by the output.

The apparatus illustrated in FIG. 1 enables the process disclosedhereinbefore to be performed under the conditions describedhereinbefore. More particularly, the apparatus has been designed inaccordance with the need to have a large section and not to be obligedto evacuate excessive amounts of liquids after each dissolution.

Referring to FIG. 1, the apparatus is mainly formed by a wide aperturetank 1, a lid 3, a plug valve 5, and two sealing-tight sleeves 7a, 7b.

The cylindrical tank 1 is made of rust-resistant steel. Its diameter issuch as to contain substantially one liter of liquid per centimeter ofheight thus producing, for instance, the following dimensions:

Mm. Diameter 360 Height 202 Thickness 2 The upper portion of the tankhas two diametrically opposed lifting lugs 9 welded to the sides, withenough lateral projection not to obstruct the lid 3, the lower portionof the tank having a ring, or more generally a telemanipulator point(not shown) adapted to facilitate the emptying of the tank by pouringwhen the tank is suspended from the lifting lugs 9.

Two glove-box temperature measuring points 11 are disposed on ageneratrix of the cylinder of the tank 1 and can receive a thermometeror thermocouple. The measuring points are disposed in parallel anddownwardly orientated at an angle of 45; they enable the temperature tobe taken at the bottom and on the surface of the liquid, whatever theamount thereof may be, up to an amount of 12 liters, with a tank of thesize given by way of example.

The top edge of the tank 1 can be outwardly curved to form a pouring lip(this feature is not shown).

The rust-resistant steel lid 3 is simply placed without a gasket on thetank 1 on to which it fits and is located by its flange 13.

The lid 3 has at its center a shaft 15 adapted to receive with slightclearance tube 17 of a plug valve 5. The shaft 15 comprises laterally awing-type set screw 19 enabling the tube 17 to be locked againstrotation. The shaft 15 is shouldered on four ribs, as 21, at 90 radii.

The end of a rib 21 is formed with an argon inlet comprising in theupper portion of the lid 3 a self-sealing connection 23, and at thelower portion of the lid 3 a vertical rust-resistant steel tube 25 whoselower portion 27 is curved to be tangential both to the bottom and wallof the tank 1, the end of the tube 25 being flattened in a ducks bill29.

Disposed at 90 from the argon inlet at the end of another rib 21 is asafety value 31.

The ribs 21 are formed with large-diameter holes, as 33, to facilitatethe handling of the lid 3.

The plug valve and the sealing-tight sleeves 7a, 7b temporarily restoreair-tightness to irradiation capsule 35 when its ends have been cut off,and also bring the capsule 35 filled with NaK in a direct and controlledman ner into communication with the tank 1 and fluid inlet 37 at theright moment.

The plug valve 5 has a direct control 39 and is of the A-turn open-closetype. The plug valve 5 is continued in its lower portion by the tube 17adapted to extend through the shaft 15 of the lid 3. The tube 17 is somachined that it can readily slide in the shaft 15 and take up positiondirectly at a satisfactory height above the bottom of the tank 1. Theupper portion of the valve 5 has a male tubular tip 41 and is normallyalways retained in the closed position.

The identical sealing-tight sleeves 7a, 7b are adapted to obliterate thecylindrical irradiation capsules 35 after their ends have been cut off,whatever the diameter of the capsules may be. The end of each sleeve 7a,7b has a. female self-sealing connection 43a, 43b respectively. Theother end of the fluid inlet 37 also has a self-sealing connection 45enabling the inlet 37 to be connected either to an inert liquidreservoir or a pure argon expanding station.

In the embodiment described, the sealing-tight connecting sleeves usedare of the kind which will now be described with reference to FIG. 2,which is an axial sectional view.

Referring to FIG. 2, a female self-sealing connection 46 of known kindis attached to the upper end of a cylindrical tip 48 whose inner cavity50 communicates with the connection 46 via a bore 52.

The inside surface of cavity 50 comprises a shoulder 54, and anintermediate ring 56, whose height is equal to the distance of theshoulder 54 from the bottom 58 of the cavity 50, is inserted in thecavity 50 hearing against the bottom 58.

Two resilient rings 60a, 60b of identical outside diameter are alsointroduced into the cavity 50. The ring 60a bears both against theshoulder 54 and the edge of the intermediate ring 56. The rings 60a, 60bare separated by a spacing washer 62 also introduced into the cavity 50.

A washer 64 is introduced into the cavity 50 to give the assembly 56,60a, 62, 60b the compression produced by a hollow nut 66 screwed into ascrewthreading 68 with which the lower inside portion of the cavity 50is formed.

Locking screws, as 70, can extend through tappings, as 72, uniformlydistributed around locking collar 74 of the hollow nut 66.

Referring again to FIG. 1, the operation of the apparatus describedhereinbefore will now be analysed.

First of all the tank 1 is filled with 2-3 liters of inert liquid, interalia a kerosene-based machining fluid, such as, for instance,Lubrisurfex, which is therefore soluble in alcohol, compatible with NaKand of a lower density.

The lid 3 is placed on the tank, the argon inlet is connected to theconnection 23 and the gas begins to circulate. The gas can circulatecontinuously and freely since the lid 3 has no gasket and is notsealing-tight and therefore allows the gas injected via conduit 25 toescape to the outside.

The inert liquid reservoir (not shown) is disposed pressurized inrelation to the tank 1 and its valve remains closed.

A rotary roller-type pump (not shown), connected in series to thecircuit to accelerate the circulation of the liquid, is stationary.

The upper portion of the irradiation capsule 35 which is disposedvertically in a vice (not shown) is cut off by a tube cutting machine orvertical sectioning machine. A few drops of inert liquid are poured intothe capsule to cover the NaK.

The sealing-tight sleeve 7a is fitted and then locked on to the cut-offportion of the capsule 35 which is again sealing-tight and can be turnedupside down, thus enabling its other end to be cut off like the firstone. The sleeve 7b is then fitted on to this other end.

With the capsule 35 still retained vertically upside down the plug valve5 is connnected via its tube 41 to the con nection 43b of the sleeve 7b.The capsule 35 is then turned over, valve downwards, whereafter the tube17 of the valve 5 is introduced into the shaft 15 of the lid 3 andlocked against rotation by the wing-type point screw 19.

The fluid inlet conduit 37 is connected to the connection 43a of thesleeve 7a.

After a number of vigorous fiushings have been performed with pure inertliquid (1-2 liters), a few cm. of alcohol are added to the inert liquidremaining in the reservoir, at the rate of 1 cm. of alcohol to 1 cm. ofNaK to be dissolved, and in the proportion of /3 pure alcohol to inertliquid. The mixture is injected into the circuit and the dissolution ofNaK begins.

To flush the capsule 35 more satisfactorily, the fluid inlet tube 37 andthe plug valve 5 can be disconnected. The capsule containing the mixtureof alcohol and inert liquid is then vigorously agitated, turned over andreconnected to continue the operation. The mixture again injected in theopposite direction has more chance of entraining the last traces of NaKtrapped in baffies.

The dissolution is monitored in the tank 1 by a thermometer probedisposed in the most suitable temperature measuring point 11 for thelevel of the liquid whose height, in the example given is 1 cm. perliter.

If the temperature exceeds 150 C., the argon flow into the tank isincreased and a further quantity of pure inert liquid is injected asrequired.

If the temperature drops below 100 C., the reaction slows down, andalcohol slightly diluted with inert liquid can be re-injected, then purealcohol. The liquid can also be vigorously agitated either with argon ormechanically, since agitation is indispensable for ensuring complete andrapid dissolution. Unless it is agitated the NaK, which is divided intosmall glomerules, is trapped in an alcoholate and foam film of the inertliquid and ceases to react with the alcohol.

To save time, after the pure alcohol has been injected, the capsule 35can be disconnected and dismantling can begin while dissolution isterminating in the tank 1.

However, before disconnection a small amount of pure inert liquid canadvantageously be injected which will insulate any traces of NaK fromthe air during the dismantling of the capsule.

The process and apparatus according to the invention are simple, directand rapid and enable irradiation capsules containing 400 cm. NaK andabove to be treated.

Safety is increased, since the alcohol used in small quantities is neverpure in the presence of NaK, the temperature can be maintained at a lowmean value of the order of 150 C., and the reaction can be readilycontrolled.

Time is saved by having a capsule available for dismantling before thecompletion of dissolution--i.e., half to one day after the start of theoperation.

Raw material is saved, since the amount of alcohol required, which isclearly dependent on the amount of NaK to be dissolved, does not exceed2-3 liters per 400 cm. of NaK. The inert liquid costs less than thealcohol, and the consumption of the former does not exceed 6-8 liters.

Lastly, the process and apparatus according to the invention enablesodium and/or potassium, which are solid at ambient temperature, to beemptied by directly re-heating the irradiation capsule with a heatingstrip.

Clearly, and as can be gathered from the foregoing, the invention is notlimited to the method of application or the embodiment thereof whichhave been described and illustrated but, on the contrary, the inventioncovers all variants.

I claim:

1. A process for dissolving an irradiated metal selected from the groupconsisting of sodium, potassium, and an alloy thereof from anirradiation capsule which comprises:

(a) adding a sufiicient amount of an inert liquid completely misciblewith alcohol to said capsule to cover said irradiated metal,

(b) adding a mixture of an alcohol and an inert liquid completelymiscible with said alcohol to said capsule; and

(c) vigorously agitating the mixture in said capsule to thereby dissolvesaid irradiated metal, said process being conducted under an argonatmosphere and the proportions of the alcohol being such that there isnot an undesirably rapid rise in the temperature of said mixture due toreaction between said irradiated metal and said alcohol.

2. The process according to claim 1 wherein the temperature of saidmixture is maintained between and C.

3. The process according to claim 1 wherein the volume ratio of alcoholto inert liquid is in the range of 1:2-4.

4. The process according to claim 1 wherein 1 cm. of alcohol is addedper 1 cm. of said irradiated metal.

5. The process according to claim 1 wherein said capsule contains atleast 400 cm. of said irradiated metal.

6. The process according to claim 1 wherein alcohol is used in an amountof 2-3 liters per 400 cm. of said irradiated metal in said capsule.

7. The process according to claim 1 wherein said step (a) is performedmore than once by flushing said inert liquid from said capsule and thenre-adding inert liquid such that said inert liquid covers saidirradiated metal before said step (b) is conducted.

References Cited Jackson: Liquid Metals Handbook Sodium NaK Supplement,USAEC, Dept. of Navy, 1955, pp. 12, 20, 114, 403.

McCormack: The Use of Cellosolve in NaK Disposal, Nuc. Sci. Abs., vol.16, N0. 20, 1962, ABS #27160, p. 3555.

CARL D. QUARFORTH, Primary Examiner R. L. TATE, Assistant Examiner US.Cl. X.R.

23-312 ME; 25230l.l W

